(a) General
This rule shall be used as the basis for calculating applicability of Regulation XIII as stated in Rule 1301(b)
and Rule 1303. This rule shall also be the basis for calculating daily emission increases and decreases used for
offset requirements and Emission Reduction Credits.

(b) Emission Increases
Emission increases for new sources and the new total emissions for modified sources shall be calculated, as approved
by the Executive Officer or designee, (1) using calendar monthly emissions divided by 30 for determination of the
required amount of offsets, and (2) on a pound per day basis for determination of BACT and modeling applicability,
from permit conditions which directly limit the emissions or, when no such conditions are imposed, from:

the maximum rated capacity; and

the maximum daily or monthly hours of operation as applicable; and

the physical characteristics of the material processed.

(c) Emission Decreases
Emission decreases from sources which are modified or removed from service shall be the actual emissions reduced
to the amount which would be actual if current BACT were applied. The emission amount shall be calculated from
the following:

The sum of actual emissions, as determined from company records, shall include annual emissions declarations
pursuant to Rule 301, or other data approved by the Executive Officer or designee, whichever is less, which have
occurred each year during the two-year period immediately preceding the date of permit application, or other appropriate
period determined by the Executive Officer or designee to be representative of the source's cyclical operation,
and consistent with federal requirements;

The sum of BACT adjusted annual emissions shall be divided by the total number of actual operation days in
each of those two years or other approved period; and

The calculated amount from paragraphs (c)(1) and (c)(2) shall be multiplied by the usage factor appropriate
to the use of the subject sources in each of the two years used for calculation, as follows:

1.0 when operated 180 days or more,
0.5 when operated 30 to 179 days, and
0.0 when operated less than 30 days.

Daily emissions shall be determined for each year. The average value shall be calculated for those two years
or other approved period.
The BACT adjustment shall not apply to facilities located in the SEDAB.

(d) Determination of Required Offsets and BACT Applicability
This subdivision shall be used for determining the amount of required offsets pursuant to Rule 1303(b)(2), and
BACT applicability pursuant to Rule 1303(a).

Modification of Existing Source.
Net emissions increase after the modification shall be calculated pursuant to Rule 1306(b) which
is the post-modification potential to emit minus either:

(A) the permitted or allowable pre-modification potential to emit; or

(B) the actual emissions calculated pursuant to Rule 1306(c)(1) if the source was never subject to Rule 213
or Regulation XIII.

(e) Determination of Emission Reduction Credit
This paragraph shall be used for determining all Emission Reduction Credits.

All Modifications:
Emission credit shall be based upon the new potential to emit calculated pursuant to Rule 1306(b) minus the decrease
calculated pursuant to Rule 1306(c).

All Shutdowns:
Emission credit shall be based upon the decrease calculated pursuant to Rule 1306(c).

The ERC shall equal the emission credit at the facility determined pursuant to paragraphs (e)(1) or (e)(2)
minus the following:

(A) The NSR balance of the facility. The NSR balance must be zero for any ERC to be granted;

(B) All Community Bank allocations;

(C) All Priority Reserve allocations; and

(D) All offsets obtained pursuant to the exemption provisions of Rule 1304.

For the purpose of ERC determination in subparagraph (e)(3)(A) above, the NSR balance may be reduced from modifications
and shutdowns by the amount of:

(A) the pre-modification potential to emit minus the post-modification potential to emit, for sources previously
subject to Rule 213 or Regulation XIII; or

(B) the actual emissions calculated pursuant to Rule 1306(c) minus the post-modification potential to emit for
sources never subject to Rule 213 or Regulation XIII.
For shutdowns, the post-modification potential to emit is zero.

(f) Air Pollution Controls
For the modification of any source installed prior to October 8, 1976, resulting from the addition of air pollution
controls installed solely to reduce the issuance of air contaminants, emissions shall be calculated, for purposes
of Rule 1303 determination only, from permit conditions which directly limit the emissions or, when no such conditions
are imposed, from:

the maximum rated capacity; and

the maximum proposed daily hours of operation; and

the physical characteristics of the materials processed.
This subsection shall not be used to calculate an Emission Reduction Credit, which shall be determined by paragraphs
(b), (c) and (e).

(g) Mobile Sources
The following mobile source emission increases or decreases directly associated with the subject sources shall
be accumulated:

Emissions from in-plant vehicles; and

All emissions from ships during the loading or unloading of cargo and while at berth where the cargo is loaded
or unloaded; and

Nonpropulsion ship emissions within Coastal Waters under District jurisdiction.

(h) PM10 Emissions
The PM10 emissions from an existing facility shall be calculated from the Total Suspended Particulate (TSP) emission
increases and decreases which have occurred since October 8, 1976, using PM10 emission factors provided in the
most recent AQMD California Environmental Quality Act (CEQA) Air Quality Handbook or as approved by the Executive
Officer or designee.